An assessment of dietary supplementation with tea catechins and rosemary extract on the quality of fresh beef

The effect of supplementation of beef cattle diets with tea catechins (TC) (1000 mg/animal/day) and rosemary extract (RE) (1000 mg/animal/day), for 103 days preceding slaughter, on the oxidative stability of M. longissimus dorsi (LD) steaks was evaluated. Dietary supplementation with TC and RE did not increase plasma total antioxidant status (TAS), LD a-tocopherol concentrations or pH. In LD steaks stored aerobically or in modified atmosphere packs (80% O-2:20% CO2) (MAP) for up to 8 days at 4 degrees C, surface redness (CIE 'a' redness value) and lipid stability (TBARS, mg MDA (malondialdehyde)/kg muscle) were not significantly improved as a result of supplementation with TC and RE. Similarly no improvement in the sensory properties and lipid stability of cooked LD slices, stored aerobically or in 30% CO2:70% N-2 for up to 11 days at 4 degrees C, was observed. An in vitro fermentation study demonstrated that TC and RE were not fermented to any great extent under simulated rumen conditions. Direct addition of TC (1000 ppm) and RE (1000 ppm) significantly (P < 0.05) improved the colour and lipid stability in LD patties stored in 80% O-2:20% CO2 for up to 8 days at 4 degrees C, thus, demonstrating the antioxidant potential of TC and RE supplements employed in the present study. (c) 2005 Elsevier Ltd. All rights reserved.